US7663370B2 - Arrangement to control antenna elements - Google Patents
Arrangement to control antenna elements Download PDFInfo
- Publication number
- US7663370B2 US7663370B2 US12/128,765 US12876508A US7663370B2 US 7663370 B2 US7663370 B2 US 7663370B2 US 12876508 A US12876508 A US 12876508A US 7663370 B2 US7663370 B2 US 7663370B2
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- 230000005540 biological transmission Effects 0.000 claims abstract description 111
- 238000007493 shaping process Methods 0.000 claims abstract description 26
- 239000003990 capacitor Substances 0.000 claims description 14
- 238000000034 method Methods 0.000 claims description 7
- 230000010287 polarization Effects 0.000 claims description 3
- 230000001747 exhibiting effect Effects 0.000 claims description 2
- 101100366711 Arabidopsis thaliana SSL13 gene Proteins 0.000 description 15
- 101100366561 Panax ginseng SS11 gene Proteins 0.000 description 15
- 230000005855 radiation Effects 0.000 description 3
- 230000004913 activation Effects 0.000 description 2
- 230000008878 coupling Effects 0.000 description 2
- 238000010168 coupling process Methods 0.000 description 2
- 238000005859 coupling reaction Methods 0.000 description 2
- 238000011156 evaluation Methods 0.000 description 2
- 230000005284 excitation Effects 0.000 description 2
- 230000006872 improvement Effects 0.000 description 2
- 238000012986 modification Methods 0.000 description 2
- 230000004048 modification Effects 0.000 description 2
- 230000010363 phase shift Effects 0.000 description 2
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- 230000009849 deactivation Effects 0.000 description 1
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Images
Classifications
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01R—MEASURING ELECTRIC VARIABLES; MEASURING MAGNETIC VARIABLES
- G01R33/00—Arrangements or instruments for measuring magnetic variables
- G01R33/20—Arrangements or instruments for measuring magnetic variables involving magnetic resonance
- G01R33/28—Details of apparatus provided for in groups G01R33/44 - G01R33/64
- G01R33/32—Excitation or detection systems, e.g. using radio frequency signals
- G01R33/36—Electrical details, e.g. matching or coupling of the coil to the receiver
- G01R33/3607—RF waveform generators, e.g. frequency generators, amplitude-, frequency- or phase modulators or shifters, pulse programmers, digital to analog converters for the RF signal, means for filtering or attenuating of the RF signal
-
- G—PHYSICS
- G01—MEASURING; TESTING
- G01R—MEASURING ELECTRIC VARIABLES; MEASURING MAGNETIC VARIABLES
- G01R33/00—Arrangements or instruments for measuring magnetic variables
- G01R33/20—Arrangements or instruments for measuring magnetic variables involving magnetic resonance
- G01R33/28—Details of apparatus provided for in groups G01R33/44 - G01R33/64
- G01R33/32—Excitation or detection systems, e.g. using radio frequency signals
- G01R33/34—Constructional details, e.g. resonators, specially adapted to MR
- G01R33/34046—Volume type coils, e.g. bird-cage coils; Quadrature bird-cage coils; Circularly polarised coils
- G01R33/34076—Birdcage coils
-
- G—PHYSICS
- G01—MEASURING; TESTING
- G01R—MEASURING ELECTRIC VARIABLES; MEASURING MAGNETIC VARIABLES
- G01R33/00—Arrangements or instruments for measuring magnetic variables
- G01R33/20—Arrangements or instruments for measuring magnetic variables involving magnetic resonance
- G01R33/28—Details of apparatus provided for in groups G01R33/44 - G01R33/64
- G01R33/32—Excitation or detection systems, e.g. using radio frequency signals
- G01R33/36—Electrical details, e.g. matching or coupling of the coil to the receiver
- G01R33/3678—Electrical details, e.g. matching or coupling of the coil to the receiver involving quadrature drive or detection, e.g. a circularly polarized RF magnetic field
-
- G—PHYSICS
- G01—MEASURING; TESTING
- G01R—MEASURING ELECTRIC VARIABLES; MEASURING MAGNETIC VARIABLES
- G01R33/00—Arrangements or instruments for measuring magnetic variables
- G01R33/20—Arrangements or instruments for measuring magnetic variables involving magnetic resonance
- G01R33/28—Details of apparatus provided for in groups G01R33/44 - G01R33/64
- G01R33/32—Excitation or detection systems, e.g. using radio frequency signals
- G01R33/34—Constructional details, e.g. resonators, specially adapted to MR
- G01R33/34046—Volume type coils, e.g. bird-cage coils; Quadrature bird-cage coils; Circularly polarised coils
Definitions
- the present invention concerns an arrangement to control an antenna arrangement as well as a device for signal splitting and a transmission method, for a magnetic resonance examination to be implemented.
- Transmit-sense techniques are under discussion for use in magnetic resonance examinations of patients in order to excite nuclear spins in a narrowly limited range in a targeted manner.
- This technique enables the effective integral of the radio-frequency magnetic field for examination to be directed only in a narrowly limited region of interest for the excitation of the nuclear spins, while also enabling the integral of the radio-frequency magnetic field (which integral is effective for the excitation of the nuclear spins) to be homogeneously adjusted in the examination region.
- the transmission antenna arrangement is fashioned in the form of a birdcage antenna.
- a radio-frequency signal is emitted via each transmission element in a transmission time period.
- the radio-frequency signals differ entirely from one another in terms of their voltages, frequencies and phases.
- Today circularly-polarized transmission signals are preferably used for examination.
- FIG. 3 shows an exemplary arrangement of a circularly-polarized transmission signal according to the prior art.
- a radio-frequency transmission signal SS arrives at a radio-frequency splitter SPLIT as an amplified transmission signal VSS via a transmission power amplifier PA.
- the radio-frequency splitter SPLIT has two inputs In 1 , IN 2 as well as two outputs Out 1 , Out 2 , wherein the amplified transmission signal VSS is connected to a first input In 1 .
- the radio-frequency splitter SPLIT divides the transmission signal VSS in two, into essentially equal transmission signals SS 1 and SS 2 , with the two transmission signals SS 1 and SS 2 being phase-shifted relative to one another by 90°.
- a first transmission signal SS 1 arrives at a first connection A 1 of an antenna arrangement ANT while a second transmission signal SS 2 arrives at a second connection A 1 of the antenna arrangement ANT.
- the two connections A 1 , A 2 form respective feed points of the antenna arrangement ANT.
- the antenna arrangement ANT is fashioned to radiate a circularly-polarized transmission signal when two transmission signals (ideally phase-shifted by 90°) are fed to it via the feed points.
- the antenna arrangement ANT is fashioned as what is known as a birdcage resonator.
- the two connections A 1 and A 2 are arranged offset on a ferrule of the antenna ANT such that a circularly-polarized transmission signal is radiated by the transmission signals phase-shifted by 90°.
- FIG. 4 shows an exemplary embodiment according to the prior art, based on FIG. 3 of the radio-frequency splitter SPLIT.
- the radio-frequency splitter SPLIT has a first input In 1 , a second input In 2 , a first output Out 1 and a second output Out 2 .
- the amplified transmission signal VSS is connected at the first input In 1 .
- the first input In 1 is connected via a first inductor L 1 with the first output Out 1 while the second input In 2 is connected via a second inductor L 2 with the second output Out 2 . It is also possible to magnetically couple the inductors L 1 , L 2 .
- the first input In 1 is connected via a first capacitor C 1 with the second input In 2 while the first output Out 1 is connected via a second capacitor C 2 with the second output Out 2 .
- the second input In 2 is connected via a resistor Z with a reference potential (here the ground) such that constant power components reflected in the outputs Out 1 , Out 2 are compensated in the resistor Z.
- the first output Out 1 is connected with the first connection A 1 of the antenna arrangement ANT while the second output Out 2 is connected with a second connection A 2 of the antenna arrangement ANT.
- the values of the inductors L 1 , L 2 , the coil coupling and the values of the capacitors C 1 , C 2 are selected such that the desired phase difference of 90° between the two transmission signals SS 1 and SS 2 results at the outputs Out 1 , Out 2 of the frequency splitter SPLIT.
- the first transmission signal SS 1 that is fed via the first output Out 1 to the first connection A 1 as a first feed point at the ferrule of the antenna ANT has a phase position of 90°.
- the circularly-polarized transmission signal is formed by the phase-shifted control at the aforementioned connections A 1 , A 2 .
- An object of the present invention to provide an improvement in examination results with low effort in magnetic resonance apparatuses of the aforementioned type.
- an arrangement to control an antenna arrangement in a magnetic resonance examination that has a device for signal splitting, which has an input and first and second outputs.
- a radio-frequency transmission channel is supplied at the input of the device for signal splitting, which contains phase-shaping components with which the transmission signal supplied at the input is divided into a first transmission signal at the first output and a second transmission signal at the second output.
- the first and second transmission signals have a phase difference therebetween that is adjusted by the phase-shaping components, by virtue of these components being switchable so as to be respectively activated or deactivated in order to modify the phase difference.
- the antenna arrangement has first and second connections for the first and second transmission signals, respectively, and is configured to radiate a circularly-polarized field as soon as the two transmission signals at the respective connections exhibit a phase difference of 90°.
- An improvement in the examination results is achieved via superimposition of the individual examination results or via the superimposition of the partial images acquired in the respective examination.
- a device for signal splitting is used in the inventive arrangement to control antenna elements of a transmission antenna arrangement in a magnetic resonance apparatus.
- This device for signal splitting has an input and at least one first and one second output, wherein a radio-frequency transmission signal is connected at the input.
- the first output of the device for signal splitting is connected with a first connection of an antenna arrangement and the second output of the device for signal splitting is connected with a second output of the antenna arrangement.
- the antenna arrangement is fashioned for radiation of a circularly-polarized transmission signal as soon as transmission signals that possess a phase difference of 90° relative to one another are present at the two connections of the antenna arrangement.
- the device for signal splitting has phase-shaping components with which the transmission signal supplied via the input is divided into a first transmission signal and a second transmission signal.
- a first transmission signal formed in this manner arrives at the first connection of the antenna arrangement via the first output of the device for signal splitting while a second transmission signal so formed arrives at the second connection of the antenna arrangement via the second output of the device for signal splitting.
- a difference between the phase position of the first transmission signal and that of the second transmission signal can be achieved via the phase-shaping components of the device for signal splitting, such that a circularly-polarized sum emission field is formed by radiation from the antenna arrangement.
- the device for signal splitting has additional switchable components. These are arranged such that the phase-shaping components can be activated and deactivated.
- the phase position of the two signals that are present at the outputs of the device for signal splitting is altered by the activation or deactivation of the phase-shaping components, such that a linearly-polarized transmission signal or an anti-circularly-polarized transmission signal is formed by radiating via the antenna arrangement.
- FIG. 1 illustrates an embodiment of an arrangement according to the invention to form a circularly-polarized transmission signal.
- FIG. 2 illustrates an embodiment of the inventive device for signal splitting, based on FIG. 1 .
- FIG. 3 shows the exemplary arrangement described above to form a circularly-polarized transmission signal according to the prior art.
- FIG. 4 shows the exemplary embodiment of the radio-frequency splitter SPLIT according to the prior art that is described above and based on FIG. 3 .
- FIG. 1 shows an embodiment of an inventive arrangement to form a circularly-polarized transmission signal.
- a radio-frequency transmission signal SS arrives as an amplified transmission signal at a radio-frequency splitter SPLIT 1 via a transmission power amplifier PA.
- the radio-frequency splitter SPLIT 1 has two inputs In 11 , IN 21 as well as two outputs Out 11 , Out 21 , wherein the amplified transmission signal VSS is connected at a first input In 11 .
- the radio-frequency splitter SPLIT 11 divides the transmission signal VSS into two essentially identical transmission signals SS 11 and SS 21 , wherein the two transmission signals SS 11 and SS 21 are preferably phase-shifted by 90° relative to one another.
- the radio-frequency splitter SPLIT 1 alternatively divides the transmission signal VSS into two essentially identical transmission signals SS 11 and SS 21 , with the two transmission signals SS 11 and SS 21 exhibiting further phase differences or no phase difference relative to one another.
- a first transmission signal SS 11 arrives at a first connection A 1 of an antenna arrangement ANT while a second transmission signal SS 21 arrives at a second connection A 1 of the antenna arrangement ANT.
- the two connections A 1 , A 2 form respective feed points of the antenna arrangement ANT.
- the antenna arrangement ANT is fashioned to radiate a circularly-polarized field when two transmission signals (ideally phase-shifted by 90°) are fed to it via the feed points.
- the antenna arrangement ANT is thus fashioned as a birdcage resonator.
- the two connections A 1 and A 2 are arranged on a ferrule of the antenna ANT such that a circularly-polarized transmission signal is formed upon irradiation via the transmission signals SS 11 and SS 21 phase-shifted by 90°.
- FIG. 2 shows an embodiment of the inventive device for signal splitting SPLIT 1 according to the invention, based on FIG. 1 .
- the radio-frequency splitter SPLIT 1 has a first input In 11 , a second input In 21 , a first output Out 11 and a second output Out 21 .
- the amplified transmission signal VSS 1 is connected at the first input In 11 .
- the first input In 11 is connected via a first inductor L 11 with the first output Out 11 while the second input In 21 is connected via a second inductor L 21 with the second output Out 21 . It is also possible to magnetically couple the inductors L 11 , L 21 .
- the first input In 11 is connected via a first capacitor C 12 with the second input In 21 while the first output Out 11 is connected via a second capacitor C 21 with the second output Out 21 .
- the second input In 21 is connected via a switch SW 5 and via a first resistor Z with a reference potential (here ground), such that constant power components reflected at the outputs Out 11 , Out 21 are compensated in the resistor Z.
- the first output Out 11 is connected with the first connection A 1 (not shown here) of the antenna arrangement ANT while the second output Out 2 l is connected with the second connection A 2 (not shown here) of the antenna arrangement ANT.
- the inductors L 11 and L 21 as well as the capacitors C 12 and C 21 serve to divide the supplied transmission signal VSS that is present at the input In 11 of the device for signal splitting SPLIT 1 into a first transmission signal SS 11 and a second transmission signal SS 21 .
- the first transmission signal SS 11 arrives via the first output Out 11 of the device for signal splitting SPLIT 1 at the first connection A 1 (not shown here) of the antenna arrangement ANT.
- the second transmission signal SS 21 arrives via the second output Out 21 of the device for signal splitting SPLIT 1 at the second connection A 2 (not shown here) of the antenna arrangement ANT.
- the two transmission signals SS 11 and SS 22 are essentially identical, but exhibit a phase difference relative to one another.
- the phase difference is set by the inductors L 11 and L 21 and the capacitors C 12 and C 21 as phase-shaping components.
- additional switchable components SW 1 through SW 5 are provided in the device for signal splitting SPLIT 1 with which the phase-shaping components L 11 , L 21 , C 12 and C 21 can be activated or deactivated.
- the phase difference between the two transmission signals SS 11 and SS 21 provided for the antenna arrangement ANT is altered by the activated or deactivated phase-shaping components L 11 , L 21 , C 12 and C 21 .
- the goal is to vary the phase difference of the two transmission signals SS 11 and SS 21 such that a circularly-polarized field or an anti-circularly-polarized field or a linearly-polarized field is alternately formed by radiation from the antenna arrangement ANT.
- a first switch SW 1 is connected to the first inductor L 11 and a second switch SW 2 is connected in parallel to the second inductor L 21 .
- a third switch SW 3 is likewise connected to the first capacitor C 12 and a fourth switch SW 4 is connected in parallel to the second capacitor C 21 .
- the values of the inductors L 11 and L 21 , the coil coupling and the values of the capacitors C 12 and C 21 are selected such that a desired phase difference of 90° results between the two transmission signals SS 11 and SS 21 at the two outputs Out 11 and Out 21 of the frequency splitter SPLIT 1 .
- the circularly-polarized transmission signal is formed upon irradiation via the activation of the antenna arrangement ANT with a 90° phase shift of the two transmission signals SS 11 and SS 21 .
- Phase difference SS11 ⁇ > SW1 SW2 SW3 SW4 SW5 SS21 Polarization open open open open closed 90° circular closed closed closed closed open 0° linear
- a switching from a circularly-polarized mode to a linearly-polarized mode is shown in this exemplary embodiment.
- phase-shaping and switchable components as well as their circuiting it is also possible to form an anti-circular mode and, in addition to the linear mode shown here, a linear mode that is perpendicular to the shown linear mode.
- the switches SW 1 through SW 5 are preferably fashioned as PIN diodes.
- polarized fields are used for magnetic resonance examinations.
- a linearly-polarized field is used in a first time segment
- a circularly-polarized field is used in a following second time segment
- a further linearly-polarized field is used in a further following third time segment.
- Each of these fields excites other currents in the body, such that a respective different examination result is acquired in each time segment.
Abstract
Description
Phase | ||||||
difference | ||||||
SS11 <=> | ||||||
SW1 | SW2 | SW3 | SW4 | SW5 | SS21 | Polarization |
open | open | open | open | closed | 90° | circular |
closed | closed | closed | closed | open | 0° | linear |
Claims (8)
Applications Claiming Priority (3)
Application Number | Priority Date | Filing Date | Title |
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DE102007024824.7 | 2007-05-29 | ||
DE102007024824A DE102007024824B3 (en) | 2007-05-29 | 2007-05-29 | Arrangement for controlling an antenna arrangement and device for signal distribution for controlling an antenna arrangement |
DE102007024824 | 2007-05-29 |
Publications (2)
Publication Number | Publication Date |
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US20080297155A1 US20080297155A1 (en) | 2008-12-04 |
US7663370B2 true US7663370B2 (en) | 2010-02-16 |
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Family Applications (1)
Application Number | Title | Priority Date | Filing Date |
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US12/128,765 Active US7663370B2 (en) | 2007-05-29 | 2008-05-29 | Arrangement to control antenna elements |
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US (1) | US7663370B2 (en) |
DE (1) | DE102007024824B3 (en) |
Cited By (2)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US20100253350A1 (en) * | 2009-04-03 | 2010-10-07 | David William Huish | Antenna assembly |
US9983279B2 (en) | 2012-10-25 | 2018-05-29 | Koninklijke Philips N.V. | Radio frequency (RF) birdcage coil with separately controlled ring members and rungs for use in a magnetic resonance (MR) imaging system |
Families Citing this family (2)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
DE102010042633B4 (en) | 2010-10-19 | 2013-02-28 | Siemens Aktiengesellschaft | Antenna circuit for an MRI system |
CN109073717B (en) | 2016-04-04 | 2021-03-23 | 皇家飞利浦有限公司 | RF transmit system with selectable drive port for magnetic resonance imaging apparatus |
Citations (5)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US6750652B2 (en) * | 2002-10-22 | 2004-06-15 | Ge Medical Systems Global Technology Company, Llc | Integrated quadrature splitter-combiner and balun |
US6982554B2 (en) * | 2004-04-29 | 2006-01-03 | General Electric Company | System and method for operating transmit or transmit/receive elements in an MR system |
US6995561B2 (en) * | 2002-04-01 | 2006-02-07 | Ge Medical Systems Global Technology Company, Llc | Multiple channel, microstrip transceiver volume array for magnetic resonance imaging |
US7019527B2 (en) * | 2002-03-21 | 2006-03-28 | Koninklijke Philips Electronics N.V. | Combiner/splitter device for an MRI system |
WO2007124246A1 (en) | 2006-04-21 | 2007-11-01 | Koninklijke Philips Electronics, N.V. | Mr involving high speed coil mode switching between i-channel linear, q-channel linear, quadrature and anti-quadrature modes |
-
2007
- 2007-05-29 DE DE102007024824A patent/DE102007024824B3/en not_active Expired - Fee Related
-
2008
- 2008-05-29 US US12/128,765 patent/US7663370B2/en active Active
Patent Citations (5)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US7019527B2 (en) * | 2002-03-21 | 2006-03-28 | Koninklijke Philips Electronics N.V. | Combiner/splitter device for an MRI system |
US6995561B2 (en) * | 2002-04-01 | 2006-02-07 | Ge Medical Systems Global Technology Company, Llc | Multiple channel, microstrip transceiver volume array for magnetic resonance imaging |
US6750652B2 (en) * | 2002-10-22 | 2004-06-15 | Ge Medical Systems Global Technology Company, Llc | Integrated quadrature splitter-combiner and balun |
US6982554B2 (en) * | 2004-04-29 | 2006-01-03 | General Electric Company | System and method for operating transmit or transmit/receive elements in an MR system |
WO2007124246A1 (en) | 2006-04-21 | 2007-11-01 | Koninklijke Philips Electronics, N.V. | Mr involving high speed coil mode switching between i-channel linear, q-channel linear, quadrature and anti-quadrature modes |
Cited By (3)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US20100253350A1 (en) * | 2009-04-03 | 2010-10-07 | David William Huish | Antenna assembly |
US8427158B2 (en) * | 2009-04-03 | 2013-04-23 | Siemens Aktiengesellschaft | Antenna assembly |
US9983279B2 (en) | 2012-10-25 | 2018-05-29 | Koninklijke Philips N.V. | Radio frequency (RF) birdcage coil with separately controlled ring members and rungs for use in a magnetic resonance (MR) imaging system |
Also Published As
Publication number | Publication date |
---|---|
DE102007024824B3 (en) | 2009-02-26 |
US20080297155A1 (en) | 2008-12-04 |
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